According to the Apple website the maximum operating altitude of the iShuffle is 3000 m (10,000 feet). Why should the altitude affect the operation of a solid state bit of electronics.

Perhaps there are certain airtight components inside (the screen, memory bits, whatever) that would risk rupturing at high altitudes.

 

I'd imagine there are parts of an LCD that are airtight, although the shuffle doesn't have an LCD... something else, perhaps?

The only bit of it I can think of that could be vulnerable to low pressure is the battery. You couldn't even use this on a stroll up Mt. Everest!!

At high altitudes, the thinner air results in a lower heat transfer from possibly hot components. As such, if there are components which may get hot, at high altitudes they might get too hot and either cause the device to shut down (as a built-in safety feature) or cause damage to the device.